Korean Patent Publication No. 2008-0052869 discloses a structure of a general secondary battery, and more particularly, a structure of a pouch type secondary battery having a bilateral symmetric and rectangular parallelepiped shape.
FIG. 1 is an exploded perspective view illustrating a pouch type secondary battery in the related art. Referring to FIG. 1, a pouch type secondary battery includes: an electrode assembly 10 having electrode tabs 11 and 12 that protrudes out of the electrode assembly 10; and a pouch exterior part 1 accommodating the electrode assembly 10 in an accommodating part 4 such that portions of electrode leads 13 and 14 connected to the electrode tabs 11 and 12, respectively, are exposed to the outside. The pouch type secondary battery is manufactured by brining an upper case 2 and a lower case 3 into contact with each other with the electrode assembly 10 accommodated in the accommodating part 4 and sealing the upper case 2 and the lower case 3.
FIG. 2 is a partial enlarged view illustrating a space between an electrode assembly and a pouch exterior part, which are included in a pouch type secondary battery in the related art.
A process of forming the accommodating part 4 in the pouch exterior part 1 may use a deep drawing method. An edge of the accommodating part 4 is rounded to prevent a concentration load from breaking the edge in the process. In particular, not only a border between a bottom surface 4B and an inner surface 4A, but also horizontal and vertical portions of the inner surface 4A are rounded. However, vertexes of the electrode assembly 10 have a right angle as illustrated in FIG. 2.
The electrode assembly 10 should be spaced apart from the pouch exterior part 1 by at least a specific distance to prevent short-circuiting. In addition, since a distance D0 between the vertexes of the electrode assembly 10 and the inner surface 4A is the minimum distance between the electrode assembly 10 and the accommodating part 4, the distance D0 should be equal to or great than a minimum distance needed for preventing short-circuiting.
However, since a distance D1 between a side of the electrode assembly 10 and the inner surface 4A of the pouch exterior part 1 is significantly greater than the distance D0 as illustrated in FIG. 2, the distance D1 is significantly greater than the minimum distance needed for preventing short-circuiting.
Thus, the volume of the electrode assembly 10 accommodated in the accommodating part 4 is significantly smaller than the volume of the accommodating part 4, which delimits electrical capacity of the pouch type secondary battery.